ANTIOXIDANT ACTIVITY OF PEANUT FLOUR FERMENTED WITH LACTIC ACID BACTERIA

Peanut flour (PF) was fermented with four strains of lactic acid bacteria. The effect of fermentation on the antioxidant activities (alpha,alpha-diphenyl-beta-picrylhydrazyl [DPPH] radical-scavenging activity, reducing power and Fe2+ chelating activity) and antioxidant compounds(phenolic acids and flavonoids) was investigated. Depending on the starter organisms used, lactic acid fermentation could increase the DPPH scavenging activity, reducing power and Fe2+ chelating activity of PF. The content of phenolic acids had a significant decrease (P < 0.05) after fermentation. Meanwhile, a significant bioconversion (P < 0.05) of rutin into quercetin was observed after fermentation. There was a good linear correlation between the EC50 value of DPPH scavenging activity (R-2 = 0.8893, P < 0.05) or reducing power (R-2 = 0.8893, P < 0.05) and the concentration of quercetin in PF. These results indicated that lactic acid fermentation might be a good process to obtain functional PF with high antioxidant activity.